Motor driven hand tool



4 y 7, 1931- J; M. CROWE uoroh muvzu mum TOOL Filed larch 24, 1930 R O T N E V m 1:212. .vvv. 2..

z/OHA/ M. CR0 E wa folz ATTORNEYS 1,644,326-of October 4,

anced between the Patented July 7, 1931 UNITED STATES P TENTYoFFicEe;

Jenn M; cnown, F oovrne'ron, xnnrucxY, nss'ienon To 'Tn'n STANLEY WORKS; on

NEW BRITAIN, connnorrou'r;

A CGRPORATION OF CONNECTICUT Moron imivnn n-A-Nn moon Application filed am 24, 1930. 7 Serial No.'438,474.

I This invention relates to portable power driven hand tools such asthe so-calle'd electric sawsadapted to be appliedbodilytoalong the same by the 7 traveling ata high linear speed, it is essential that guardingl means be provided which protect the operator from the entire blade periphery. The provision of such guarding means is the subject matter 2f my Patent No.

Also, and as illustrated and described in my Patent No. 1,7 80,174 of November 4, 1930, in such a tool it is convenient and desirable toarrange the cutting blade forward ly of the motor-which drives the same, and

to provide the tool with two handles one generally over the blade, theother generally rearward of the motor, whereby in working position the tool is bal handles, the entryof into the work'may be controlled primarily by the forward handle, and the ,tool may be carried about by the rearward handle alone,

in a position generally do pending from this handle. Particularly in such depending position the blade the blade, lying as it does .in proximity with the oper'ators knees, will if running and unless properly guarded inevitably seriouslyinjure the operator. I we For this reason the guarding means as shown in my patents above referred to,-have been arranged to be yieldably urged to full guarding position and there latched, the for releasing actua-' 455 latch being arranged tion tby engagementwith the Occasionally, however, as where a cut isgto be made other'th-an beginning at an edge of the work, it is more practicable to release the O guard bydirect operator control.

stood that the axis 7 tudinally of the tool and that of the blade More specifically, therefore, an object'of my invention is to arrange in a tool of the class described, guarding means niovably mounted on the tool frame to advance or reced'e toguard or expose a cutting portion of the toolblade, automatic means effective in all tool positions and tending to advance the guardingmeans, ni'eansalso effective in all tool positions for automatically securing the guarding means against recession, a handlefor manipulat ng the tool, and means associated withthe handle for operator-ops 1 erated release of the guarding means while the handle is grasped. i V

I A further object of the invention is to provide for optional operatonope'rat'ed release of guarding means arranged for normalrelease by engagement of the tool with with the work. 7 r

Another object of the invention is to provide for operator-operated release ofuthe guarding means in a tool having its blade located at its forward end and a pair of longitudinally spaced han 'les one at the blade end; and associating the release means with the forward tool handle for actuation by the hand grasping this handle, whereby unless the blade, end of the tool is supported by its handle, the guard cannot be released from full-guarding position.

The exact nature of my invention together with further objects and advantages thereof will be apparent from the following description taken in connection with the accompanying drawings, which Fig. 1 shows,

in side elevation, a tool of the class to which reference has been made and in which an embodiment of'm'y' invention has been incorporated. the tool beingv partly broken away to show details of construction; and dotdash lines indicating alternate positions of certain of the parts ;'and Fig-'2 is a sectional detail as from line. 22, Fig; 1 7

With reference now to the drawings, the principal parts of the tool are the frame 1 secured with the'inotor 2' and having operatively mounted thereon to be driven by the motor, a cutting blade 3; 'it being underof the motor runs longitransverse of the tool and in front of the motor, proper gearing, forming no part oi this invention, being provided for the purose.

The frame includes a fixed guard portion 4 which encloses the upper portion oi? the blade in hoodlike fashion. and a forward handle 5 serves to connect the base of the frame adjacent the motor with the upper extremity of the guard 4. Hinged to the frame as at 6 for telescoping movement within the fixed guard 4, is a movable guard 7 having a surface 8 adapted to engage and travel along the work, it being understood that the work engaging or runner portion or" the movable guarding means is slotted in the plane of the blade 3 to allow passage of the working portion of the blade therethrough.

The fixed guard 4 is provided with a slot 9 arcuate about the axis 6, and the movable guarding means is provided with a roller 10 mounted upon a lever 11 which swings on an axis 12, and has an arm 13 with a too 14 projecting, when the lever is in the position indicated, below the work engaging surface of the movable guarding means. The slot 9 terminates downwardly in the oil-set por tion 15 in which the roller 10 is shown seated, and a spring 16 urges the lever 11 in counter-clockwise direction and consequently the roller 10 into the oil-set 15, when the roller is aligned therewith, and OtlI-QNVlS', against the inner edge of the slot 9. A bolt 17 is adjustable along the slot 9 and engageable by the roller 10 to limit telescoping movement of the movable guarding means. This guarding means is urged to its extreme downward position by a spring 18.

It will be apparent that the movable guarding means is mounted to advance or recede to guard or expose a cutting portion of the blade, that the spring serves as automatic means elfective in all tool positions tending to advance the guarding means, and that the cooperation of the roller 10 with the slot 9 and particularly off-set l5 there-at serves as means also effective in all tool positions for automatically securing the movable guarding means against recession. Likewise when the toe 14 is pressed against the edge of work to be cut the roller 10 is disengaged irom the off-set 15 whereupon the main portion of the tool including the motor 2 and the fixed guard 4 may tilt in clockwise direction upon the axis 6 to project a working portion. of the blade 3 below the work engaging surface 8 of the so-called movable guard 7; such tilt, and thus the depth of cut, being limited by the adjusted portion of the stop bolt 17.

Pivotally mounted upon the guard por tion 4 of the fran e as at 19, is a latch release lever 20 having a thumb piece 21 extending adjacent the handle 5, and a finger portion 22 extending adjacent the roller 10. The lever 20 is free to move on its axis, and when it is the thumb piece 21 is depressed, moving the lever 20 from its full line position to its indicated dot-dash position, the roller 10 will be moved by the finger 22 from the notch 15 into its indicated dot-dash position at the base of the slot 9, this movement being against the spring 16 and unlatching the guard members 4 and 7 for telescoping movement against the action of the spring 18.

Rearward of the motor 2 are arranged a handle 23 and a switch-box 24, the switchbox containing a switch controlling the motor, and thus the saw blade, subject to manipulation of the trigger lever 25, a cable 26 being arranged to establish power connection to the switch.

As to operation, the rear handle of the tool is grasped by the right hand and the forward handle 5 by the left hand. The tool is nicely balanced between the handles, the center of gravity lying somewhere withinthe confines of the motor, whichis the heaviest portion of the tool. The tool is thus presented to the work, and where a cut is to begin at an edge of the work the latch is released by engagement of the toe 14 therewith. The motor being energized by the right forefinger acting on the switch lever 25 the blade is set in motion. the handle 5 is depressed, tilting the frame about the axis 6 to lower a working portion of the blade below the runner 8, and the tool is advanced until the blade bites into the work. The blade, once the work is engaged, draws itself thereinto, and the blade being lowered to its limit as determined by the position of the stop bolt 17, the handle 5 may be released and the tool advanced by means of the handle 23 alone to complete the cut.

Normally the motor is then stopped by release of the switch trigger 25 and the tool removed from the work by its two handles. Should, however, the tool by any carelessness run oil? the end of the work, or atany time be dislodged from the work, and swing downwards toward the operators knees, the movable guard means immediately snaps back and is latched in the full guarding position shown, so that the operator is not injured as he would otherwise be. Such functioning of the guarding means is important, particularly since once the tool is started on its cut, theforward handle 5 may be and often is in practice released, the tool being guided merely by the rear handle 28, so that it or when run oil the work the tool tends to swing downwards against the operator.

hen a cut is to be started in a work surface it is difficult to release the latch by means of the toe 14. Under such conditions, provided the handle 5 is grasped, the thumb piece 21 may be depressed, unlatching the guard so that the blade may be pressed into the work by means of the handle 5.

Thus it is only While the handle 5 is grasped that the latch may be released directly by operator effort, and even though unlatch'ed, immediately the handle?) is re leased the guard is in a sense pre-set for movement and latching in full guarding position, instantly the tool be moved accidentally or otherwise to a position involving danger to the operator.

What I claim is: p

1. In a portable power driven hand tool adapted to be applied bodily to the work and moved along the same by the operator, a frame, a cutting blade operatively mounted thereon, a motorfor operating said blade, guarding means movably mounted on said frame to advance or recedc to guard or expose a cutting portion of said blade, and comprising a base having a surface adapted to engage and travel along the work, auto matic means effective in all tool positions and tending to advance said guarding means, means also effective in all tool positions for automatically securing said guarding means against recession, a handle arranged adj acont said blade, and means, associated with said handle for operator-operated release of said guarding means while the handle is graspe 2. In a portable power adapted tobe applied bodily to the work and moved along the same by the operator, a frame, a cutting blade operatively mounted thereon, a motor for operating said blade, guarding means movably mounted on said frame to advance or recede to guard or expose ,a' cutting portion of said blade, and

comprising a base having a surface adapted to engage and travel along the work, automatic means effective in all tool positions and tending to advance said guarding means,'means also effective in all tool posi-' tions for automatically securing said guarding means against recession, a handle for manipulating the tool, and means for releasing said guarding means adapted for actuation by engagement with the work and means associated with said handlefor operator-operated release of said guarding means while said handle is grasped.

3. In a portable power driven hand tool adapted to be applied bodily to the work and;

moved along the same by the operator, a frame, a cutting blade operatively mounted thereon. a motor for operating said blade, a

fixed guard rigidly associated with the frame for guarding a portion of said blade,

guarding means movably mounted on said frame'to advance or recede to guard or expose a cutting portion of said "blade and comprising a base having a surface adapted to engage and travel along the work, automatic means effective in all; tool positions and tending to advance said guarding means, latch means also effective in all tool posidriven hand tool tions for locating the limit of advance of 7 fully advancedposition, said fixed guard and said movable guarding means being arranged to guard the entire cutting edge of said blade when the guarding means is in. said fully advanced position, a handle for: manipulating the tool, means adapted for actuation by engagement with the work for releasing said latch to allow recession of said guarding means, and means associated with said handle for actuation by the operator to effect release of said latch.

4:. In a portable power driven hand tool adapted to be applied bodily to the work and moved alo-ngthe same by the operator, a frame, a cutting blade operatively mounted at the forward end thereof, a motor for operating said blade and arranged rearwardly thereof, guarding means movably mounted on said frame toadvance or recede to guard or expose a cutting portion of said blade, and comprising a base having a surface adapted to engage andtravel along the work, automatiomeanseffective in all tool positions and tending to advance said guarding means, means also effective in all tool j 5. In a portable power driven hand tool adapted to be applied bodily to the work i and moved along the sameby the operator,

a frame, a cutting blade operatively mountedgat the forward endth'ereof, a motor for operating said blade and arranged rearwardly thereof, guarding means movably mounted on said frame to advance or recede to guard or expose a cutting portion of said blade, and comprising a base having a surface adapted to engage and travel along the work, automatic means effective in all tool positions and tending to advance said guarding means, means also effective in all tool positions for automatically securing said guarding means against recess1on,-a pair of v longitudinally spaced handles for manipulating the tool, means associated with the rearward handle for controlling said motor,

and means associated with the forward handle for releasing said guarding means while said forward handle is grasped.

6. In a portable tool, a frame, a cutting blade operatively mounted thereon, means for operatlng said blade, guarding means adapted to advance or retreat to guard or expose a cutting portion .of said blade,

means tending to advance said guarding means, means for securing said guarding means against accidental retreat, means adapted for actuation by engagement with the Work for releasing said guarding means to allow the same to retreat, a handle "for said tool, and means associated with said handle for operaton-operated relez se of said guarding means while the handle is grasped. In testimony whereof I hereby affix my signature.

JOHN M. CROVVE. 

